U.S. Pat. No. 7,234,533 to Gambier discloses a seal assembly maintaining a seal under various conditions by storing energy that can be used to insure maintenance of the contact forces of the seal. It is a seal element for use in a packer deployed in a well, comprising a support sleeve, a sealing layer enclosing the support sleeve, and a tube with slots adapted to radially extend against the above mentioned support sleeve in response to the tube being axially compressed to press the sealing layer against a wall enclosing the packer to establish a sealing contact between the sealing layer and the well.
US2012/0261127 Saudi Arabian Oil Company describes a sliding stage cementing tool and method wherein an inflatable packer is inflated by injection from fluid in an annular cylinder. Check valves keep the packer inflated after the injection. The inflatable packer forms a cementing foundation in the annulus.
WO91/05134 and U.S. Pat. No. 5,024,273 Coone, “Cementing apparatus” describes a cementing tool for placing cement within the annulus between a casing string and a well bore. A stage collar has a packing element which is inflatable by a liquid provided through narrow passageways.
U.S. Pat. No. 3,948,322 describes a multiple stage cementing tool with an oil-inflatable packer forming a basis in the annulus for cementing.
US2010/0051276 Rogers et al. describes a stage cementing tool for use in cementing a casing in a well. The stage cementing tool includes a housing with a mechanically set packer so seal against the well. A hydraulically actuated opening sleeve will move in the housing to uncover flow ports in the housing and allow flow therethrough into the well. An end ring 66 is arranged for being displaced so as for compressing a rubber packer axially, resulting in the rubber packer expanding radially to close the annulus.
The cementing tool of Rogers has a packer assembly for being set mechanically and a second stage cementing sleeve which is set hydraulically. A cementing plug is landed in a seat in the cementing sleeve, hydraulic pressure is then used to move the cementing sleeve.
Disadvantages of Rogers' stage cementing tool are:                Activation using a cementing plug which must be drilled out after the cementing operation.        Moreover, a significant disadvantage of Rogers' device is that once the cementing process is complete, the sleeves and seats which present obstacles in the full-bore diameter of the casing, and/or cement in the casing, must be drilled out before further operations may be carried out.        The design requires much space, which is a problem if the cementing collar shall have the same pressure rating as the casing.        The radial reach of the compressed seal element is rather small as the radial expansion is due to axial compression only. This will strongly limit the usefulness to other than cementing into a small inner diameter of a surrounding casing. Due to this point and the space requiring design mentioned above, this will incur an increased dynamic counterpressure during circulation in the annulus.        When the plug is set, a pressure increase will activate the mechanism, a step which cannot be undone.        
U.S. Pat. No. 5,738,171 Szarka, Halliburton, describes well cementing inflation packer tools and methods. The tool includes a tubular housing with a packer inflating port and a packer inflating port opening sleeve sliding within the housing. The opening sleeve is moveable between closed and opening positions by a cementing plug. An external packer sleeve has a pressurized fluid inflatable packer element and a cement port in it is sealingly arranged over the outer surface of the housing and the packer inflating port. The external packer sleeve has a passageway from the packer inflating port to the inflatable packer element and a check valve in the passageway. A fluid rupturable port has a predetermined rupture pressure sealingly arranged over the cementing port. Cement may be filled into the packer.
A casing cementing system called C-flex, which is marketed by the applicant Archer Oil Tools, comprises a casing section with an internal sleeve operated valve to the annular space. The internal sleeve and aperture are provided with gaskets so as to make the Cflex casing section gas proof. The sleeve is operated to open and close from within the casing bore by a drill pipe string mounted manipulation tool with a set of “dogs” protruding from the tool stem. The set of dogs of the drill pipe string conveyed tool engages with a corresponding key ring of the correct dimension within the internal sleeve. When the sleeve is displaced the valve to the annulus is opened so as for cement to be injected from a port in the tubular tool stem out into the casing and subsequently out through the opened valve. So-called swab cups prevent cement from extending along the tool stern in the interior of the casing. The combined manipulating and cementing tool with swab cups is very similar to the wash tools shown in Nelson's (Schlumberger) 2006 textbook “Well Cementing”, p. 530 and FIG. 14-34 in chapter 14 on “remedial cementing”.
Such C-flex casing sections may be installed in the casing string in several places for immediate use after the installation of the casing, or for potential subsequent remedial cementing.